Will a brief cognitive-behavioral training program, aimed at changing explanatory style and delivered preventively, lower the future rate of depression in people at risk? We will use a population of ambulatory college students with pessimistic explanatory style, who are thereby at heightened risk for depression. Individuals will be randomly assigned to one of two conditions: 1) a four-week, eight- (two-hour) session cognitive-behavioral training program with homework, or, 2) a no-treatment, assessment-only control. The program follows a manual we have developed and piloted for changing explanatory style with nondepressed people proactively. It consists of training in recognizing and modifying maladaptive thinking, particularly depressogenic explanatory style, thought stopping, assertion training, and graded task assignment. All participants will then be tracked across a threeyear follow-up period. We will monitor depressive symptoms and occurrence of depressive episodes and other related psychopathology. We hypothesize that the preventive training will reduce the subsequent depressive symptomatology and the frequency of episodes of depressive disorder. Further,, we intend to examine the mechanisms by which this preventive effect is-mediated. In particular., we hypothesize that the training will produce a lasting, more optimistic explanatory style, which, in turn, will mediate lower risk for depression. If this program is successful, it will provide a model for preventive training which may markedly and inexpensively lower the rate of depression across America.